package network.tcp;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TcpEchoServer {
    private final ServerSocket serverSocket;

    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }

    public void start() throws IOException {
        System.out.println("服务器，启动！");
        ExecutorService service = Executors.newCachedThreadPool();
        while (true) {
            Socket clientSocket = serverSocket.accept();//会频繁申请文件资源，需要关闭
//            Thread t = new Thread(() -> processConnection(clientSocket));
//            t.start();
            service.submit(() -> processConnection(clientSocket));//只好一点
        }
    }

    private void processConnection(Socket clientSocket) {
        System.out.printf("[%s:%d] 客户端上线\n", clientSocket.getInetAddress(), clientSocket.getPort());
        try (InputStream inputStream = clientSocket.getInputStream();
             OutputStream outputStream = clientSocket.getOutputStream()) {
            while (true) {
                Scanner scanner = new Scanner(inputStream);
                if (!scanner.hasNext()) {
                    System.out.printf("[%s:%d] 客户端下线\n", clientSocket.getInetAddress(), clientSocket.getPort());
                    break;
                }
                String request = scanner.next();
                String response = process(request);
                PrintWriter printWriter = new PrintWriter(outputStream);
                printWriter.println(response);
                printWriter.flush();
                System.out.printf("[%s:%d] req=%s resp=%s\n", clientSocket.getInetAddress(), clientSocket.getPort(),
                        request, response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                clientSocket.close();//关闭资源，fin结束报文段的发送于此触发
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    protected String process(String request) {
        return "echo: " + request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer server = new TcpEchoServer(9091);
        server.start();
    }
}
